jwright36

Hello building my airboat and I've started construction with cardboard that is going very well so I've decided to fiberglass it and use it as the final product. Just a few questions. What weight would be ideal for the hull of the boat seeing as it is taking the most abrasive forces? Lowes and walmart sell bondo brand cloth but has no label of the weight of the cloth, looks very thick though. I've heard 6oz works well. Probably go thicker on motor mounts etc. Then finally for the deck I'm skinning in CF. Any advice appreciated, thank you!

jwright36

1QwkSport2.5r

Wow, cardboard.... Yikes! Hope you're using an electric motor and light batteries. If you can't use wood at all, use some standard 6-8oz cloth. Get it from your hobby shop. The Bondo brand stuff has a horrible weave. It will require a ton of sanding to get it smooth enough.

For resin - either get some finishing resin from the hobby shop or get some 60min epoxy from a big box store and thin it with methanol or acetone. Finishing resin can be thinned too, but it's already pretty thin to start with. If you thin epoxy down, do it ONLY after you mix the resin and hardener together [well].

jwright36

Thank you for the info sir! The correct 1/8 in plywood I'd like will have to be ordered online and in the size needed 24x48. This started as a mock up then I just thought hmm why not fiberglass it inside and out!? You don't thi k even with some heavy mat or cloth it will withstand a 48cc gasser? Weight shouldn't be a problem given its cardboard, if anything it being under weight would be the problem. Gas tank will be up front in the middle to help also.

1QwkSport2.5r

48cc gasser on a cardboard hull? Sorry, but HELL NO. Fiberglass or not, you're gonna have problems IMHO. No offense, but I would not but any fuel engine on that hull. Small electric motor only.

jwright36

No offense taken at all sir haha. Understand completely! Got to working on it and just wanted it quicker than waiting on materials haha. But you are right do it right the first timE and not have to come back and do it over!

1QwkSport2.5r

I would just hate for you to lose an engine and electronics to a possibly flimsy hull. What you could (and should IMO) do is use the cardboard to practice building and glassing. It would be a bit of a waste of materials, but it would be good prep for the real deal.

One word of caution in regard to epoxy resin - if you mix a large quantity (like 1-2oz or more at a time), mix it in a Dixie cup or something and then dump it out onto a paper plate with a good lip on it. Epoxy cures through an exothermic reaction (heat) and in a large quantity in a small container will cause the resin to heat up very quickly (it can burn you!) and it can catch fire. I found that out the hard way the first time I mixed resin. 2oz of 60min resin got so hot it burned the cup in 5 minutes and was hard as a rock in 15min.

jwright36

Haha I have heard that! Doesn't sound like a good time at all. That is a great idea. This will go back to a practice run for sure. Just a spit ball idea. It's always good to have some practice passes with fiberglass and the procedure first I would imagine!

1QwkSport2.5r

Absolutely. Good luck.

jwright36

Well fiberglass came in today and get to start that task tomorrow! I would love to make this a functioning airboat in general, 1QwkSport2.5r being as big as it is what would your suggestions on motor prop combos for a twin motor setup be sir?

1QwkSport2.5r

Small electric, and probably not a twin. As for size and batteries - no clue. Small. I have reservations on the cardboard, so I don't even recommend using it, to be honest. Maybe Crispyspa will chime in or send him a PM. He's the electric airboat guru. He got a 1/4 scale SI3 to hit 74mph (mind you that's a 23lb boat). Try dropping him a PM?

jwright36

Thank you sir I will shoot him a message!